Apparatus and methods for delivering prostheses to luminal bifurcations

ABSTRACT

A catheter for delivering luminal prostheses comprises a catheter body having an expandable member near a distal end. The prosthesis has a side hole, and a guidewire extends beneath a proximal portion of the prosthesis and over the exterior of the expandable member. A distal end of the guidewire is retracted proximally from the closest point on the side opening to reduce possible interference with catheter advancement.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/044,392 (Attorney Docket No. 32164-705.401, now U.S. Pat.No. ______), filed Mar. 9, 2011, which is a divisional of U.S. patentapplication Ser. No. 11/406,139 (Attorney Docket No. 32164-705.201, nowU.S. Pat. No. 7,922,754), filed Apr. 17, 2006, which claims benefit ofU.S. patent application Ser. No. 60/672,735 (Attorney Docket No.32164-705.101), filed Apr. 18, 2005 and No. 60/758,726 (Attorney DocketNo. 32164-707.101), filed Jan. 12, 2006, the full disclosures of whichare incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates generally to medical devices and methods.More particularly, the present invention relates to apparatus andmethods for delivering stents and other luminal prostheses tobifurcations in the vasculature and other body lumens.

Stenting is a common medical procedure used in the vasculature and otherbody lumens. Over the last decade, the use of stents and other vascularprostheses has become wide spread in the revascularzation of stenoticblood vessels where the blood vessel is first dilated and a stent placedto maintain vessel patency following the procedure. The stents aretypically small, mesh-like tubular devices which are expanded in situ.They are typically formed from a metal and can be coated with drugs orother active agents.

The use of stents, and in particular drug-coated stents, has been verysuccessful in the treatment of many forms for coronary artery disease.The success of stents, however, has been more limited for the treatmentof lesions occurring at vessel bifurcations. While the disease in themain vessel is generally treated successfully, the outcome in thesmaller or “side branch” vessel is often less successful. The lack ofsuccess is believed to result from a lack of coverage by the stent atthe ostium (opening) of a lesion and the resulting lack of drug deliveryto that area.

To overcome at least some of these shortcomings, the inventors hereinhave developed a stent having a self-opening side portion which coversthe side branch ostium when the stent is opened in the main blood vesselor other body lumen. This stent is described in co-pending applicationSer. No. 11/330,382 (Attorney Docket No. 022246-000240US), filed on Jan.10, 2006, the full disclosure of which is incorporated herein byreference.

Stents having side holes or openings for alignment with side branchlumens are generally known in the art, and a variety of protocols andsystems for delivering such stents to vascular and other luminalbifurcations are known. Of particular interest of the present invention,several guidewire systems have been proposed for delivering such stentsto a luminal bifurcation and for aligning the side hole with a sidebranch ostium prior to expansion of the stent. For example, U.S. Pat.No. 5,749,825 to Fischell et al. describes introducing a ballooncatheter carrying the stent over a main vessel guidewire. A side branchtube is positioned beneath a proximal portion of the stent and over theexterior of the balloon. A distal portion of the side branch tubeextends through a side hole in the stent and permits advancement of aside branch guidewire into the side branch vessel. While generallyeffective for aligning the side hole of the stent with the side branch,the unconstrained distal portion of the side branch tube which extendsfrom the side hole can interfere with advancement of the catheterthrough the vasculature. The presence of the side branch tube canincrease the profile of the catheter, thus making it more difficult tointroduce to smaller blood vessels and body lumens. Finally, Fischellsuggests no specific approach for assuring that the two guidewires havenot become crossed at the bifurcation so that the side hole ismisaligned with the side branch ostium.

A similar stent and catheter structure is described in U.S. Pat. No.6,048,361, to Von Oepen. The guidewire tube of the '361 patent (referredto as a “hollow chamber”), however, is shown to extend to the center ofthe side opening in the stent. While this reduces the likelihood thatthe guidewire tube will interfere with catheter advancement, the chanceof such interference is not completely eliminated. The distal tip of theguidewire tube (hollow chamber) remains exposed through the side holeand can potentially impede advancement of the catheter.

Other patents showing the use of side tubes for delivering stents havingside holes to bifurcated body lumens include U.S. Pat. No. 6,099,497;U.S. Pat. No. 6,165,195; and U.S. Pat. No. 6,596,020, and variousrelated patents and publications.

Attempts have been made to design a dedicated stent for bifurcationlesions. These stents are designed to support and deliver drugs to atleast part of the bifurcation area.

However, current solutions usually require two balloons, two sheaths andtwo guide wires to facilitate both alignment and expansion of the stent.

These solutions suffer from a variety of shortcomings. One example ofsuch shortcoming is high profile and cumbersome delivery system relativeto conventional stents, resulting in difficult delivery through tortuousanatomy and through tight lesions. It creates a need for aggressivepredilation that causes trauma to the vessel.

Another example of such shortcoming is due to the need for accurateaxial and rotational positioning of the stent facing the side branch.These devices are mostly “self aligning,” meaning that the stent ispushed to its axial position by the physician while rotationalorientation is dictated by the side sheath. These devices do not provideindication for rotational orientation and do not provide the physicianwith means to torque the stent into position. Occasionally the highprofile of these devices causes friction between the device and thelesion and may prevent the stent from aligning properly. Without meansto torque the stent into position and without indication of properposition, the stent may be expanded with the side access facing thevessel wall instead of facing the side branch.

For these reasons, it would be desirable to provide improved apparatus,systems, and methods for delivering stents and other prostheses tobifurcated vasculature and other body lumens. In particular, it would bedesirable to provide for the delivery of stents having a side openingsuch that the side opening is properly aligned with the ostium of a sidebranch lumen prior to expansion of the stent or other prostheses. Itwould be still more desirable if the delivery systems were compatiblewith stents having self-opening side structures in which to find theside opening in the stent. Such devices, systems, and methods should becompatible with small diameter (low profile) catheter structures, shouldreduce or eliminate any structure which exposed at or through the sideopenings in the stent or prostheses, and should allow for conformationof proper positioning of the side hole prior to expansion of the stentor other prostheses. At least some of these objectives will be met bythe inventions described herein below.

2. Description of the Background Art

Patents and published applications describing bifurcated stents anddelivery systems include U.S. Pat. Nos. 4,994,071; 5,609,627; 5,749,825;5,755,735; 5,928,248; 6,048,361; 6,099,497; 6,165,195; 6,221,098;6,210,429; 6,325,826; 6,596,020; 6,599,316; 6,676,691; 6,682,536;6,689,156; 6,692,483; 6,709,440; 6,706,062; 6,835,203; 6,884,258; U.S.Publication Nos. 2002/0042650; 2002/0156516; 2002/0173835; 2003/0187494;2003/0195606; 2004/0015227; 2004/0019302; 2004/0133268; 2004/0138737;2005/0010278; 2005/0015108; 2005/0060027; 2005/0102,019; 2006/0036315;EP 1 2554 506 B1; and German Patents DE 297 08 803 U1; and DE 29 701 758U1.

BRIEF SUMMARY OF THE INVENTION

The present invention provides apparatus and systems for the delivery ofvascular and other luminal prostheses having side openings atbifurcations in the vasculature or other body lumens. Bifurcations willusually include a main branch vessel and a side branch vessel, where thecylindrical body of the prosthesis will be positioned within the mainbranch with the side opening aligned with an ostium or opening into theside branch. While the apparatus and systems will be particularly usefulfor delivering prostheses having self-opening side structures, as taughtin co-pending U.S. patent application Ser. No. 11/330,382, the fulldisclosure of which has previously been incorporated herein byreference, it should be appreciated that they are also useful fordelivering any stent or prosthesis having a side hole or other openingand/or side structure which is to be aligned with the ostium of a sidebranch.

In a first specific aspect of the present invention, a delivery cathetercomprises a catheter shaft having a proximal end and a distal end, withan inflation hub or other inflation means attached to its proximal end.An expansion member, such as an inflatable balloon, is disposed near thedistal end of the shaft, and an expandable prosthesis is mounted overthe expansion member. The expandable prosthesis will typically be formedfrom a deformable metal so that expansion of the expansion member willenlarge the prosthesis from a small diameter configuration to a largediameter configuration which is anchored within the main vessel of thevasculature or other body lumen being treated. The prosthesis willfurther have a side hole, optionally in the form of a self-opening sidestructure, which is to be aligned with an ostium of the side branchlumen after the prosthesis has been expanded. The phrase “side hole”includes any opening or structure which is to be aligned with an ostiumof a side branch lumen or vessel. The side hole may simply be a cell ora slit in the prosthesis structure which is preselected to be alignedwith a side branch vessel but which is otherwise similar to other cells,slits, or the like in the prosthesis. More usually, however, the sidehole will be an enlarged or enlargeable cell which is distinguishablefrom the adjacent or remaining structure of the prosthesis. In otherembodiments, the “hole” comprises a self-opening or balloon openableperipheral structure which is intended to bridge the circumference ofthe side branch ostium after the prosthesis is opened in the mainbranch. Such alignment is achieved with a guidewire structure which isdisposed over the expansion member (optionally over or within the foldsof an inflatable balloon) and beneath a proximal portion of theprosthesis. In an initial configuration of the catheter, the guidewirestructure will extend to a holding location which is spaced proximallyfrom the side hole of the prosthesis, usually by a distance of at least1 mm, preferably at least 2 mm, and more preferably at least 3 mm.

The guidewire structure may have a variety of configurations. In onespecific embodiment, the guidewire structure comprises a guidewire tubewhich carries the guidewire in a lumen thereof. The guidewire tube willbe positioned between the prostheses and the expandable member, as justdescribed, and the guidewire will remain in the guidewire tube with adistal end retracted fully within the tube during advancement of thecatheter to a position near the bifurcation. In an alternativeembodiment, the guidewire structure may comprise an elongate slidehaving a channel which slidably receives the guidewire. The channel canbe formed, for example, as a “half tube” with an open top which can beoriented either toward the balloon or toward an inner surface of theprosthesis. The use of a slide may be preferred over the use of a fullguidewire tube since it can reduce the resulting profile or diameter ofthe catheter. As a second alternative, the guidewire structure mayconsist essentially or only of the guidewire itself. That is, theguidewire may be directly placed between the inner surface of theprosthesis and the outer surface of the expandable member without anyfurther structure surrounding it. In all cases, however, the guidewireand any other structure associated with the guidewire will be withdrawnproximally of the side hole by the requisite distances described above.

The delivery catheters of the present invention will preferably furthercomprise a central guidewire extending distally from the catheter shaft.In some instances, the central guidewire could be fixed to (combined andimmobilized with) the catheter shaft, but more often the centralguidewire will be a conventional moveable guidewire, either in aover-the-wire design (which extends fully or almost fully through theentire catheter shaft), in a rapid exchange design where the guidewireextends only through a distal portion of the catheter shaft, or in otherconventional simplified exchange designs.

In a second aspect of the present invention, a delivery cathetercomprises a catheter shaft, an expansion member, and an expandableprosthesis having a side hole, generally as described above. Theguidewire is disposed over the expansion member and beneath at least aproximal portion of the prosthesis so that the guidewire is advanceablethrough the side hole. In this particular embodiment, the guidewire mayextend partially or fully to side hole and in some instances through theside hole of the prosthesis even while the catheter is being advancedthrough the vasculature toward the bifurcation. In this aspect of theinvention, the catheter shaft includes a split lumen along at least aportion of its length for removably receiving a proximal portion of theside guidewire. The split lumen is particularly useful for constrainingthe side guidewire in embodiments where a main guidewire is receivedonly in a distal portion of the catheter shaft (typically to facilitaterapid exchange). In such instances, the side guidewire could becomeentangled or twisted with the main guidewire if both guidewires werefree of the catheter shaft structure. The split lumen would preferablybe used to constrain the side guidewire, but could be used for the mainor the side guidewires. In other embodiments, it would be possible toenlarge the split lumen to receive both wires or to provide two splitlumens for receiving both the main guidewire and the side guidewire.

Other features of the delivery catheter having the split guidewire lumenare generally the same as those described in connection with the firstaspect of the present invention. The delivery catheter will usuallycomprise a central guidewire, either a fixed central guidewire ormoveable central guidewire. The side guidewire may be received in aguidewire tube, in a guidewire slide, or maybe disposed directly betweenthe expandable member and an inner surface of the prosthesis. In thisaspect of the invention, the guidewire and any other guidewire structuremay also extend through the side hole in the prosthesis even when thecatheter is in its delivery configuration for advancement through themain vessel.

In a third aspect of the present invention, methods are provided fordelivering a prosthesis having a side hole (as defined above) to aluminal location. The methods comprise advancing a catheter over acentral guidewire through a main lumen, such as an artery or other bloodvessel, to position the prosthesis near the bifurcation. A sideguidewire is then advanced through the side hole into a branch lumen ofthe bifurcation, and the prosthesis is eventually expanded at thebifurcation with the side hole aligned with the side branch. In order toassure that the side hole is properly aligned with the ostium or openingof the side branch, radiopaque markers are provided on the prosthesisand/or on the guidewire so that the positions may be observed underfluoroscopy. If it is observed that the catheter is rotated so that theguidewire crosses the prosthesis to reach the side branch, or the sidehole is directed away from the ostium, then it is clear that the sidehole is not properly aligned with the side branch ostium. Thus, thecatheter may be rotated until it is apparent under the fluoroscopicimaging that the guidewire is no longer crossing the prosthesis and theside hole is therefore rotationally aligned with the side branch ostium.Rotation is achieved by applying torque on the device through the hub.In order that the device distal area will rotate in conjunction to therotation of the hub the catheter needs to transmit torque effectively.This can be achieved by the use of torque resistant shafts for thedistal area.

This method for rotationally aligning the prosthesis is compatible withany of the catheter systems described previously where the sideguidewire extends through the side hole of the prosthesis to aid inalignment of the side hole with the side branch ostium, includingsystems which require a separate balloon to deploy a side structure onthe prosthesis into the ostium of the side branch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a delivery catheter constructed inaccordance with the principles of the present invention.

FIG. 2 is an enlarged view of a distal portion of the catheter of FIG.1, shown with an expanded prosthesis in broken line.

FIG. 3 is an enlarged view of a proximal portion of the deliverycatheter of FIG. 1.

FIG. 4 is a cross-sectional symmetric view taken along line 4-4 of FIG.3.

FIG. 5 illustrates a side guidewire which is useful in the apparatus andmethods of the present invention.

FIGS. 6A and 6B illustrate positioning of a guidewire tube beneath aprosthesis mounted on an expandable member in accordance with theprinciples of the present invention.

FIGS. 7A and 7B illustrate positioning of a guidewire slide positionedbeneath the prosthesis and over an expandable member in accordance withthe principles of the present invention.

FIGS. 8A and 8B illustrate a guidewire which is positioned withoutadditional supporting structure beneath a prosthesis and over andexpandable member in accordance with the principles of the presentinvention.

FIGS. 9A through 9E illustrate use of the delivery catheters of thepresent invention for implanting a prosthesis having a side hole at anostium of a side branch in the vasculature of a patient in accordancewith the principles of the present invention.

FIGS. 10A and 10B illustrate an optional aspect of the method of thepresent invention for assuring that the side guidewire does not crossthe prosthesis as the prosthesis is expanded.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a delivery catheter 10 carries a prosthesis 12having a side hole 15 (FIG. 2) on an expandable member 14, such as aninflatable balloon of the type normally employed in stent delivery. Thedelivery catheter 10 further comprises a distal section 16, anintermediate section 18, and a proximal section 20, where the sectionsare arranged to provide an elongate catheter body to support theexpandable member 14 so that it may be delivered intraluminally orintravascularly to a target site in a generally conventional manner.Typically, the distal and intermediate sections 18 will be relativelymore flexible than the proximal section 20. A proximal hub 22 having aconnector 24 for connection to a balloon inflater is attached to aproximal end of the proximal section 20. The hub can have any designincluding a y-shaped hub, a hub with flexible connector, and the like. Acentral guidewire 26 is received through the balloon and exits from aport near the proximal end of distal section 16 of the catheter body.Although illustrated as a “rapid exchange” design, it will beappreciated that the shaft of the delivery catheter 10 could also beadapted for over-the-wire introduction over the central guidewire 26, orany other know or future design.

Of particular interest to the present invention, a side guidewire 28 isdisposed beneath a proximal portion of the prosthesis 12 and over theexpandable member 14. As described in more detail in connection withFIGS. 6-8, the side guidewire may be disposed in a guidewire tube,guidewire slide, or without further supporting structure. As shown inFIG. 2, the side guidewire 28 is disposed in a guidewire tube 30 whichextends beneath the prosthesis 12. The side guidewire 28 passes into alumen within the catheter shaft through a port 34 and passes back out ofthe shaft through a proximal port 36 (FIG. 1). The prosthesis 12 willhave a side hole 15, preferably in the form of a self-opening or otherside structure, as shown in broken line in FIG. 2. Details of aself-opening side structure are provided in copending application Ser.No. 11/330,382, the full disclosure of which has previously beenincorporated herein by reference.

Referring now to FIGS. 3 and 4, the proximal section 20 of the deliverycatheter may optionally be formed with a split side lumen 34 forremovably receiving the side guidewire 28, as best seen in FIG. 4. Thissection can be formed over a hypotube 36 with a polymeric extrusion 38over the hypotube forming the split guidewire lumen 34. Open lumen 40through the hypotube will serve as the inflation lumen for the catheter.The split side guidewire lumen is particularly advantageous since itallows the guidewire to be constrained during advancement of thecatheter. By constraining the side guidewire, the chance of crossing orotherwise entangling the side guidewire 28 with the main guidewire 26 isgreatly reduced. It would be possible, of course, to provide a secondsplit guidewire for the main guidewire, or in other instances deemingguidewire could be received within a central lumen of the catheter shaftin a conventional over-the-wire configuration. In alternativeembodiments, the polymeric tube may be extended separately and may beseparate from the hypotube.

Referring now to FIG. 5, an exemplary side guidewire 40 comprises around proximal section 42, a reduced diameter round transition section44, and a flat distal section 42. A radiopaque coil 46 joins the distalend of the flat section 42 optionally with an atraumatic distal sphere48. The guidewire can be formed from stainless steel, shape memorymaterials, or other conventional guidewire materials, and will havedimensions normally associated with guidewires for intravascular orother luminal uses. The delivery catheters of the present invention canbe used with a variety of other guidewires, including very low profileguidewires which can further reduce the diameter of the catheter system.

Referring now to FIGS. 6 through 8, positioning of the side guidewire 28beneath a proximal portion of prosthesis 12 and over the expandablemember 14 will be described for several embodiments of the presentinvention. In the embodiment of FIGS. 6A and 6B, guidewire 28 isdisposed in a guidewire tube 50 which is located beneath a proximalportion of the prosthesis 12 and over an outer surface of the expandablemember 14. A distal tip 52 of the guidewire tube is located by a minimumdistance 1 from the closest point of the side hole 15. The distance 1will generally be at least 1 mm, preferably being at least 2 mm, andoften being 3 mm or more. In the catheter introduction configuration,the guidewire 28 will be fully retracted within the guidewire tube 50,as shown in FIG. 6A. Once the catheter has been advanced to thebifurcation, the guidewire 28 may be advanced distally and through theopening 15 so that it may be guided to the side branch, as shown in FIG.6B.

In a first alternative embodiment as shown in FIGS. 7A and 7B, the sideguidewire 28 may be disposed in a guidewire slide 60 having a region 62which is open on the side adjacent the prosthesis 12. Thus, theguidewire 28 may be received in a channel formed by the open region ofthe slide 60 which provides a guide to help advance the guidewirethrough the opening 15, as shown in FIG. 7B. As with the previousembodiment, the distal most end of the guidewire 28 and guidewire slide60 will be maintained by the minimum distance 1 from the closest portionof the opening 15.

In a second alternative embodiment, guidewire 28 may be disposeddirectly between the inner surface of the prosthesis 12 and the outersurface of the expandable member 14, as shown in FIGS. 8A and 8B. Again,the distal tip of the guidewire 28 will be maintained at a minimumdistance 1 from the closest portion of the opening 15 in the prosthesis.Once the catheter has been advanced to a location near the bifurcation,the side guidewire may be advanced through the opening, as shown in FIG.8B.

Referring now to FIGS. 9A through 9E, an example of the delivery ofprosthesis 12 using the delivery catheter 10 to a branch lumencomprising a main vessel MV and a side vessel SV will be described.First, the central guidewire 26 is advanced through the main vessel to apoint beyond the ostium O of the side vessel SV, as shown in FIG. 9A.The catheter 10 may be advanced over the central guidewire 26 in theconventional manner until the prosthesis 12 approaches the ostium O ofthe side vessel SV. In FIG. 9B, the side guidewire 28 is shown in theguidewire tube 50, but it will be appreciated that any of the guidewirestructures of FIG. 6-8 could be employed.

The side guidewire 28 is next distally advanced through the opening 15of prosthesis 12, as shown in FIG. 9C, and the guidewire is thenadvanced through the ostium O and into the side vessel SV, as shown inFIG. 9D. At that point, the catheter may be advanced so that the opening15 in the prosthesis 12 approaches and eventually aligns with the ostiumO. The balloon or other expandable member 14 may then be inflated sothat the prosthesis 12 expands within the main vessel MV and the sideopening (shown as a self-opening side structure) aligns with the ostiumO, as shown in FIG. 9D. In one embodiment, the side guidewire will havea stiffer section near its distal end to improve system alignment.

In a preferred aspect of the present invention, the side guidewire 28may be radiopaque (or include radiopaque markers) and/or radiopaquemarkers may be provided on a side of the prosthesis 12 aligned with theside opening 15. The use of such radiopaque structures allows thephysician to easily determine whether the prosthesis is rotationallymisaligned with the ostium O of the side vessel SV. As shown in FIG.10A, when the prosthesis is rotationally misaligned, the side guidewirewill extend across the prosthesis 12. Expansion of the prosthesis 12 inthis position will of course not result in alignment of the side opening15 with the ostium O. In cases where a separate balloon is used todeploy a side structure, such misalignment can dissect or perforate theartery or other treated lumen. The catheter can then be torqued torotate the prosthesis 12 so that the opening 15 is adjacent the ostium Owith the side guidewire 28 positioned as shown in FIG. 10B. Thisconfiguration is readily observed under fluoroscopic imaging since theradiopaque markers 70 on the prosthesis 12 (generally adjacent to theopening 15) will be adjacent to the ostium O. Additionally, theradiopaque side guidewire 28 can be observed going directly from theopening into the side branch vessel SV. In this configuration, theprosthesis may be deployed by expanding the expandable member 14.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A delivery catheter comprising: a catheter shafthaving a proximal end and a distal end; an expansion member disposednear the distal end of the shaft; an expandable prosthesis having a sidehole and being mounted over the expansion member; and a guidewirestructure disposed over the expansion member and beneath a proximalportion of the expandable prosthesis; wherein the side hole of theprosthesis comprises an enlarged cell distinguishable from the adjacentor remaining structure of the prosthesis, and wherein the side hole ofthe prosthesis is configured to bridge the circumference of a sidebranch ostium after the prosthesis is expanded in a main branch vessel.2. A delivery catheter as in claim 1, wherein the guidewire structurecomprises a side guidewire slidably received in a passage of a guidewiretube.
 3. A delivery catheter as in claim 1 wherein the guidewirestructure comprises a side guidewire slidably received in a channel ofan elongate slide.
 4. A delivery catheter as in claim 1, wherein theguidewire structure consists essentially of a guidewire which directlycontacts an inner wall of the prosthesis and an outer surface of theexpansion member.
 5. A delivery catheter as in claim 1, furthercomprising a central guidewire extending distally from the distal end ofthe catheter shaft.
 6. A delivery catheter as in claim 5, wherein thecentral guidewire is fixed.
 7. A delivery catheter as in claim 5,wherein the central guidewire is moveable.
 8. A delivery catheter as inclaim 1, wherein the holding location is spaced at least 1 mm proximallyof the side hole.
 9. A delivery catheter as in claim 1, wherein theholding location is spaced at least 3 mm proximally of the side hole.10. A delivery catheter as in claim 1, wherein the expandable prosthesiscomprises a radiopaque marker adjacent the side hole of the prosthesis.11. A delivery catheter as in claim 1, wherein the catheter shaft isadapted to transmit torque such that rotating the proximal end rotatesthe expandable prosthesis disposed near the distal end.
 12. A deliverycatheter as in claim 1, wherein the catheter shaft is adapted to selfalign as the shaft is advanced through the main branch vessel.
 13. Adelivery catheter as in claim 1, wherein the catheter shaft comprises adistal section, an intermediate section, and a proximal section, whereinat least one of the distal and intermediate sections is more flexiblethan the proximal section.